xref: /illumos-gate/usr/src/lib/libm/common/m9x/frexpl.c (revision c5bab7026b8e0ac44b25ee08507ea360f177d844)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
24  */
25 /*
26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
27  * Use is subject to license terms.
28  */
29 
30 #pragma weak frexpl = __frexpl
31 
32 #include "libm.h"
33 
34 #if defined(__sparc)
35 
36 long double
37 __frexpl(long double x, int *exp) {
38 	union {
39 		unsigned i[4];
40 		long double q;
41 	} xx;
42 	unsigned hx;
43 	int e, s;
44 
45 	xx.q = x;
46 	hx = xx.i[0] & ~0x80000000;
47 
48 	if (hx >= 0x7fff0000) {	/* x is infinite or NaN */
49 		*exp = 0;
50 		return (x);
51 	}
52 
53 	e = 0;
54 	if (hx < 0x00010000) {	/* x is subnormal or zero */
55 		if ((hx | xx.i[1] | xx.i[2] | xx.i[3]) == 0) {
56 			*exp = 0;
57 			return (x);
58 		}
59 
60 		/* normalize x */
61 		s = xx.i[0] & 0x80000000;
62 		while ((hx | (xx.i[1] & 0xffff0000)) == 0) {
63 			hx = xx.i[1];
64 			xx.i[1] = xx.i[2];
65 			xx.i[2] = xx.i[3];
66 			xx.i[3] = 0;
67 			e -= 32;
68 		}
69 		while (hx < 0x10000) {
70 			hx = (hx << 1) | (xx.i[1] >> 31);
71 			xx.i[1] = (xx.i[1] << 1) | (xx.i[2] >> 31);
72 			xx.i[2] = (xx.i[2] << 1) | (xx.i[3] >> 31);
73 			xx.i[3] <<= 1;
74 			e--;
75 		}
76 		xx.i[0] = s | hx;
77 	}
78 
79 	/* now xx.q is normal */
80 	xx.i[0] = (xx.i[0] & ~0x7fff0000) | 0x3ffe0000;
81 	*exp = e + (hx >> 16) - 0x3ffe;
82 	return (xx.q);
83 }
84 
85 #elif defined(__x86)
86 
87 long double
88 __frexpl(long double x, int *exp) {
89 	union {
90 		unsigned i[3];
91 		long double e;
92 	} xx;
93 	unsigned hx;
94 	int e;
95 
96 	xx.e = x;
97 	hx = xx.i[2] & 0x7fff;
98 
99 	if (hx >= 0x7fff) {	/* x is infinite or NaN */
100 		*exp = 0;
101 		return (x);
102 	}
103 
104 	e = 0;
105 	if (hx < 0x0001) {	/* x is subnormal or zero */
106 		if ((xx.i[0] | xx.i[1]) == 0) {
107 			*exp = 0;
108 			return (x);
109 		}
110 
111 		/* normalize x */
112 		xx.e *= 18446744073709551616.0L;	/* 2^64 */
113 		hx = xx.i[2] & 0x7fff;
114 		e = -64;
115 	}
116 
117 	/* now xx.e is normal */
118 	xx.i[2] = (xx.i[2] & 0x8000) | 0x3ffe;
119 	*exp = e + hx - 0x3ffe;
120 	return (xx.e);
121 }
122 
123 #else
124 #error Unknown architecture
125 #endif
126